When manufacturing paper, especially tissue and fluff, static electricity, measured as static potential, can be a problem. It can cause discharges or sparks, which disturb the production. Furthermore, if the dry fibres have a high static potential the fibres tend to glue themselves to process equipment such as mills, defiberizers and pipes. The fibres are accumulated and discharged as big lumps which create problems when forming the final fluff product. Since the formation of the final fluff product usually is made from dry fibres, an even distribution of the fibres is important and lumps of fibres should be avoided. In tissue production a product with too high or too low static potential can result in extensive dusting which in turn can result in dust explosions. Attempts to reduce the static potential usually lead to deterioration of the effect of the debonder, which is added to enhance the softness of the paper.
Conventional fluff and tissue as well as methods for making such paper are well known in the art. For products made from tissue or fluff, softness is an important feature. The debonder interferes with the natural fibre-to-fibre bonds that occur during sheet formation in the papermaking process. This reduction in bonding provides a softer, or less harsh, sheet of paper.
Most debonders contain quaternary ammonium surfactants. Since producers and consumers experience a growing environmental concern, quaternary ammonium surfactants are not always accepted. The quaternary ammonium surfactants are generally toxic to aquatic organisms and generally considered undesired chemicals.
WO 98/07927 describes the production of soft absorbent paper products using a softener. The softener comprises a quaternary ammonium surfactant, a non-ionic surfactant as well as strength additives. The softening agent is added to the cellulosic suspension before the paper web is formed.
It is an object of the present invention to provide a papermaking process that can reduce the static potential.
It is a further object of the present invention to provide a papermaking process that can control the static potential while maintaining the effect of the debonder.
It is still a further object of the present invention to provide a papermaking process, which gives the possibility to control the static potential so it can be adjusted to a certain value.